Silicone-polycarbonate copolymers are known in the art as are the copolymers of the preferred embodiments of the present invention, i.e., silicone-polycarbonate block copolymers.
For example, Vaughn et al., U.S. Pat. No. 3,189,662, disclose organopolysiloxane-polycarbonate block copolymers and a method for preparing them. The reference mentions that the described copolymers are useful as surface coatings for appliances, as insulation, as coatings for rods and wires, as binding material for parts and laminates, and in adhesive formulations. The reference does not mention blending such silicone-polycarbonate copolymers with any other thermoplastic or thermoset resin copolymer or blend thereof.
Molari, U.S. Pat. Nos. 4,027,072 and Re. No. 32,406, discloses polycarbonate laminates in which the laminae are bonded by polysiloxane-polycarbonate block copolymers.
It is also known that polyphenylene ether and polyester resins can be blended together along with reinforcements and/or flame retardant additives to produce thermoplastic compositions with various desired properties such as flame retardance and reduced melt viscosity.
For example, Abolins et al., U.S. Pat. No. 4,013,613, disclose thermoplastic compositions which include admixtures of polyphenylene ether and polyester resins. Included within the thermoplastic compositions of the patentees are those wherein the admixtures of resins are in combination with a reinforcing amount of a reinforcing filler. In combination, the three-component thermoplastic compositions included within the invention are those which do not delaminate or separate when cooled, and those which do not manifest a failure to form structurally useful compositions because of reduced gross physical properties, chemical resistance, macroscopic appearance and the like.
Betts et al., EP-A No. 0133641, disclose flame retardant thermoplastic compositions of admixtures of a polyester resin and a flame retardant agent comprised of a combination of a polyphenylene ether resin, an organic phosphate and a stable brominated material.
Lee, U.S. Pat. No. 4,123,410, discloses a thermoplastic composition of an admixture comprised of polyphenylene ether, a plasticizer and an amount of a polyester sufficient to reduce the melt viscosity of said composition without substantially reducing the heat distortion temperature and ductility properties. The preferred amount of polyester is 2-5% by weight.
Also, Lee et al., U.S. Pat. No. 4,206,154, disclose self-extinguishing thermoplastic molding compositions comprising a polyphenylene ether resin, a styrene resin, a halogenated aromatic flame retardant, ferrocene and from 1-15% by weight of a fatty-acid terminated saturated polyester.
Also, in copending commonly-owned application, Ser. No. 891,497 filed July 29, 1986, abandoned, there are disclosed highly compatible polymer blends having a high degree of impact resistance and solvent resistance. These blends comprise at least one polyphenylene ether or blend thereof with at least one polystyrene, at least one poly(alkylene dicarboxylate), at least one elastomeric polyphenylene ether-compatible impact modifier, and at least one polymer containing a substantial proportion of aromatic polycarbonate units.
Illustrative of the linear polyesters are the poly(alkylene dicarboxylates) and especially the poly(alkylene terephthalates). In copending, commonly owned application, Ser. No. 010,867 filed Feb. 4, 1987, there are disclosed similar polymer blends which are highly compatible and have high solvent resistance and favorable tensile properties but which are particularly useful in applications where impact strength is not the primary consideration.
Finally, Seiler et al., U.S. Pat. No. 4,672,086 disclose self-extinguishing thermoplastic polyester molding materials containing a linear aromatic polyester resin, a polyphenylene ether resin, a phosphate-containing compound and a filler. The compositions may optionally contain an aromatic polycarbonate.
The compositions of the present invention are believed to describe a novel class of thermoplastic materials comprised of, preferably, a blend of silicone-polycarbonate block copolymer and a compatibilized polyphenylene ether resin/polyester resin alloy.